Auditory processing of speech involves high-level neural computation. An experimentally accessible model system using learned sounds for vocal communication is found in songbirds, which use their songs to communicate during courtship or aggressive behaviors. Previous work revealed several circuits involved in auditory processing of these vocal signals in songbird brains. One of them, the anterior forebrain pathway (AFP), plays a critical role in the learning process, during which a juvenile bird learns to reproduce the song of a tutor. AFP neurons display very selective responses to complex auditory stimuli such as the bird's own song or tutor songs. Although these are among the most selective auditory responses recorded in any species, the precise role of the AFP in auditory processing remains unclear. Our work has the long term goal of understanding how complex auditory signals for vocal communication are processed in the forebrain, and how neuromodulators alter this processing. Our specific hypothesis is that auditory information comes to area X exclusively from the pallial (cortex-like) nucleus HVC and further processing is influenced by local GABA and dopamine. We propose that dopamine release in the BG induces a reduced response to afferent pallial inputs, and thus a reduced response to song playback. The BG would then exert a diminished influence on their target structures in high dopamine condition. PUBLIC HEALTH RELEVANCE: These experiments take advantage of the strong parallels that we have demonstrated between songbird basal ganglia circuits and those of mammals. Together, they address mechanisms of auditory processing of vocal communication signals in basal ganglia structures that underlie learning of a vocal behavior in juveniles and modification of such behavior in adults. The results will guide understanding of the role of the basal ganglia in processing complex auditory stimuli, and could shed light on disorders of vocal communication in which the basal ganglia are implicated, such as autism and Tourette's syndrome.